BAD THING: Your enjoyment of this issue may be limited by how much you enjoy The Legion of Superheroes and how amused you are by the concept of Superboy Prime being an unsubtle parody of the stereotypical comic book fan.
GOOD THING: That being said, if you do like metatextual humor, this is a REALLY funny issue. The plot, such as it is, centers upon Superboy Prime (who is currently trapped in our universe) reading this comic, finding out that he is supposed to die in the next issue and desperately trying to find any information he can about the next issue... all while being taunted by a Black Lantern Earth-3 Lex Luthor.
Oh, and the Legion back-up story isn't too bad either, even though I really don't care about Legion and some of the backstory was lost on me, though it was explained well.
The Final Verdict: A good issue, if you have a decent sense of humor regarding the character of Superboy Prime and the concept of characters who know they are in a story. I found it hillarious but your mileage may vary.